This past three weeks below freezing destroyed all of my water Barrels. They completely froze and busted at the seems. 15 or so cans lost means I'm not replacing them. These trees can either survive without protection or die. I'm over it.

One solution would have been to place large plastic trash bags inside of the bins and then line the edges with foam and bunched newspaper so the water would be able to expand after freezing.

Or to just fill the barrels with a bunch of smaller water bottles that are each only 90% filled.

Also, the propylene glycol people buy for fog machines can act as an anti-freeze if mixed in the water. It's pretty environmentally benign. (Although you'd have to use one third by weight propylene glycol to lower the freezing point to 0°F, I just looked it up on a graph)

Denaturated ethanol goes for about $70 for a 10-gallon container, but isn't much better at lowering the freezing point. (30% by weight will lower the freezing point to -5°F)

Hmm, I wonder what would happen if you just placed a long cylindrical plastic bag full of styrofoam chips down the middle of the barrel. That way the water would have room to expand. Maybe tie it down with a cinder block.

This past three weeks below freezing destroyed all of my water Barrels. They completely froze and busted at the seems. 15 or so cans lost means I'm not replacing them. These trees can either survive without protection or die. I'm over it.

I had some plastic garbage cans that leaked. Put large plastic garbage bags in them, filled with water and they did not leak all winter. They were in a hoop greenhouse that warmed during the day so can't say how they would have fared in very cold conditions.

Thanks guys. I've been doing this cold hardy citrus thing for 6 years now, and never had barrels bust like this. I think it usually gets warm enough to keep them from fully freezing, but the past few weeks were just too much prolonged cold. The idea of paper/ foam barrier around edges of barrel would allow for expansion, but I think we need the water as. Close to the tree as possible to benefit from the heat given off as water freezes. Also, lowering the freezing point of the water may work against the effort of warming the tree since we're making it harder for the water to freeze and therefore harder for water to give off the heat from freezing, no? What a science project, huh?

Some years ago I was using solutions of different concentrations of Epsom salt MgSO4 instead of water for palm tree protection.This permits to have a more gradual heat liberation due to the liquid/solid phase transition

Millet, the thermocubes are little power strips that I plug space heaters into for my good citrus which I cover with plastic/ little greenhouses. The barrels that busted were just placed next to citranges and Ichang lemons out in the open with no other protection really. The one Ichang lemon had three barrels surrounding it and then plastic over it's pvc frame; those Barrels froze and busted too. I'm not too worried about the poncyrus hybrids since my dunstans went through the past two winters without protection at all, not even water barrels. I'll probably loose the Ichang lemons, but I need to get over them anyway since they really don't stand a chance of getting tall enough to produce fruit here anyway.